ATMEGA328P-20PU Atmel, ATMEGA328P-20PU Datasheet - Page 18

• Manufacturer Part Number: ATMEGA328P-20PU
• Manufacturer: Atmel

Specifications of ATMEGA328P-20PU

• Cpu Family: ATmega
• Device Core: AVR
• Device Core Size: 8b
• Frequency (max): 20MHz
• Interface Type: SPI/TWI/USART
• Program Memory Type: Flash
• Program Memory Size: 32KB
• Total Internal Ram Size: 2KB
• # I/os (max): 23
• Number Of Timers - General Purpose: 3
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• On-chip Adc: 6-chx10-bit
• Instruction Set Architecture: RISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Through Hole
• Pin Count: 28
• Package Type: PDIP
• Lead Free Status / Rohs Status: Compliant

7.3
8025K–AVR–10/09
SRAM Data Memory
Figure 7-3
The ATmega48P/88P/168P is a complex microcontroller with more peripheral units than can be
supported within the 64 locations reserved in the Opcode for the IN and OUT instructions. For
the Extended I/O space from 0x60 - 0xFF in SRAM, only the ST/STS/STD and LD/LDS/LDD
instructions can be used.
The lower 768/1280/1280 data memory locations address both the Register File, the I/O mem-
ory, Extended I/O memory, and the internal data SRAM. The first 32 locations address the
Register File, the next 64 location the standard I/O memory, then 160 locations of Extended I/O
memory, and the next 512/1024/1024 locations address the internal data SRAM.
The five different addressing modes for the data memory cover: Direct, Indirect with Displace-
ment, Indirect, Indirect with Pre-decrement, and Indirect with Post-increment. In the Register
File, registers R26 to R31 feature the indirect addressing pointer registers.
The direct addressing reaches the entire data space.
The Indirect with Displacement mode reaches 63 address locations from the base address given
by the Y- or Z-register.
When using register indirect addressing modes with automatic pre-decrement and post-incre-
ment, the address registers X, Y, and Z are decremented or incremented.
The 32 general purpose working registers, 64 I/O Registers, 160 Extended I/O Registers, and
the 512/1024/1024 bytes of internal data SRAM in the ATmega48P/88P/168P are all accessible
through all these addressing modes. The Register File is described in
ter File” on page
Figure 7-3.
shows how the ATmega48P/88P/168P SRAM Memory is organized.
Data Memory Map
11.
(512/1024/1024 x 8)
160 Ext I/O Reg.
64 I/O Registers
Data Memory
Internal SRAM
32 Registers
0x02FF/0x04FF/0x04FF
0x0000 - 0x001F
0x0020 - 0x005F
0x0060 - 0x00FF
0x0100
ATmega48P/88P/168P
”General Purpose Regis-
18